Diols phosgene

The first HFIP-based polycarbonate was synthesi2ed from bisphenol AF with a nonfluorkiated aromatic diol (bisphenol A) and phosgene (121,122). Incorporation of about 2—6% of bisphenol AF and bisphenol A polycarbonate improved the dimensional stabkity and heat-distortion properties over bisphenol A homopolycarbonate. Later developments in this area concern the flame-retardant properties of these polymers (123,124). 

Polycarbonates are prepared commercially by two processes Schotten-Baumaim reaction of phosgene (qv) and an aromatic diol in an amine-cataly2ed interfacial condensation reaction or via base-cataly2ed transesterification of a bisphenol with a monomeric carbonate. Important products are also based on polycarbonate in blends with other materials, copolymers, branched resins, flame-retardant compositions, foams (qv), and other materials (see Flame retardants). Polycarbonate is produced globally by several companies. Total manufacture is over 1 million tons aimuaHy. Polycarbonate is also the object of academic research studies, owing to its widespread utiUty and unusual properties. Interest in polycarbonates has steadily increased since 1984. Over 4500 pubflcations and over 9000 patents have appeared on polycarbonate. Japan has issued 5654 polycarbonate patents since 1984 Europe, 1348 United States, 777 Germany, 623 France, 30 and other countries, 231. 

By application of the Corey-Winter reaction,vicinal diols 1 can be converted into olefins 3. The key step is the cleavage of cyclic thionocarbonates 2 (1,3-dioxolanyl-2-thiones) upon treatment with trivalent phosphorus compounds. The required cyclic thionocarbonate 2 can be prepared from a 1,2-diol 1 and thio-phosgene 4 in the presence of 4-dimethylaminopyridine (DMtVP) ... 

D) Synthesis of ABC ring system In order to prepare the molecule for closure of the 8-membered B ring, diol 22 was converted to its cyclic carbonate by treatment with phosgene in the presence of KH. 

Chemical/Physical. At 230 °C, endrin isomerizes to an aldehyde and a ketone. When heated to decomposition, hydrogen chloride and phosgene may be released (NIOSH, 1997) but residues containing an aldehyde (15-20%), a ketone (55-60%), a caged alcohol (5%), and other volatile products (15-20%) were reported (Phillips et al., 1962). In water, endrin undergoes nucleophilic attack at the epoxide moiety forming endrin diol (Kollig, 1993). 

Meprobamate Meprobamate, 2-methyl-2-propyl-l,3-propandiol dicarbamate (5.2.2) is synthesized by the reaction of 2-methylvaleraldehyde with two molecules of formaldehyde and the subsequent transformation of the resulting 2-methyl-2-propylpropan-l,3-diol (5.2.1) into the dicarbamate via successive reactions with phosgene and ammonia [48-50]. 

Homopolycarbonates based on 1 and 2 have been prepared by several groups. The interfacial polycondensation typical for the synthesis of aromatic polycarbonates is not useful with alditols, including 1, because they are water-soluble and less acidic than diphenols. The 1-based homopolycarbonate was prepared by phosgena-tion of the sugar diol, with phosgene or diphosgene in pyridine-containing solvent mixtures at low temperatures. The polycondensation of the isosorbide bischloro-formate in pyridine is an alternative approach. 

Notably, an almost quantitative yield of DMC and 1, 2-diols can be attained under the optimized reaction conditions. Additionally, the catalyst is easily reused in almost consistent in yield and selectivity. This process eliminates the requirement for toxic and wasteful feedstocks such as phosgene and carbon monoxide and has successfully been applied to synthesize the other symmetric dialkyl carbonates and 1, 2-diols. 

Major uses of aniline include the manufacture of / ,//-methylene diphenyl diisocyanate (MDI), which is polymerized with a diol (HO-R-OH) to give a polyurethane. Two moles of aniline react with formaldehyde to give />,//-methylenedianiline (MDA), which reacts with phosgene to give / ,//-methylene diphenyl diisocyanate. Toluene diisocyanate (TDI) also reacts with a diol to give a polyurethane, but polyurethanes derived from />,//-methylene diphenyl diisocyanate are more rigid than those from toluene diisocyanate. 

Carbonic acid is a diacid with suitable diols, it can form polyesters. For example, when phosgene (the acid chloride of carbonic acid) reacts with a diol, the product is a polycarbonate ester). The following equation shows the synthesis of Lexan polycarbonate a strong, clear, and colorless material that is used for bulletproof windows and crash helmets. The diol used to make Lexan is a phenol called bisphenolA, a common intermediate in polyester and polyurethane synthesis. 

Oleic acid was converted to the erythro diol 264 or the threo diol 258 by reaction with permanganate or hydrogenperoxide respectively. The threo compound 258 was converted to the 9,11-dioxahomoprostanoids. Reaction with paraformaldehyde formed 259 or 260, phosgene converted the diol into 261 whereas reaction with thiophosgene gave compound 262. 

Oxazincs are formed starting from nitriles and diols. 1,3-Amino alcohols react with phosgene or urea derivatives to give l,3-oxazin-2-ones. -Amino acids are converted to... 

Polycarbonates are formed from phosgene and a diol. The most widely used polycarbonate is Lexan, a lightweight, transparent material used in bike helmets, goggles, catcher s masks, and bulletproof glass. 

Phosgene and 2,4-hexadiyn-l, 6-diol react to form 2,4-hexadiyn-l, 6-bischloroformate, which... 

A 2- or 6-hydroxy-substituted purine can be prepared from the corresponding 4,5-diamino-pyrimidinol by cyclization with an acid, ester, ortho ester, or amide. If the ring closure is performed with reagents such as urea, alkyl chloroformates, urethanes, phosgene, and alkyl isocyanates, the 8-hydroxypurines are formed. Various xanthine and uric acid derivatives have been prepared by the condensation of 5,6-diaminopyrimidine-2,4-diols with formic acid. Purin-2-ol (1) was prepared by this route from 4,5-diaminopyrimidin-2-ol and ethyl orthoformate. ... 

Carbon dioxide or phosgene is employed to form uric acid (9) from 5,6-diaminopyrimidine-2,4-diol. Another route to 9 uses the fusion of 5,6-diaminopyrimidine-2,4-diol with urea. ... 

When the polycarbonate of bisphenol A was made interfacially in a non-solvent for the polymer the distribution of molecular weights showed two clear maxima and was unusually broad [40]. This was probably a consequence of the two-step process often employed in the preparation of polycarbonates here, the first step yields low-molecular-weight polymer from phosgene and the aqueous alkaline solution of the aromatic diol, then an accelerator salt and more alkali and phosgene are added in the second step. Polycarbonates prepared in the melt and in solution show the expected essentially statistical distribution of molecular weights [40]. Polycarbonates have also been prepared from bisphenols and bisphenol bischloroformates studies of this reaction in nitrobenzene solution have shown it to be second order [79]. 

Cyclic carbonates are introduced through the use of phosgene or a phosgene equivalent and a base (pyridine). They are most stable to acid hydrolysis and are removed under rather strongly basic conditions. Interestingly, they can protect both cis- and frani-vicinal diols. 

A few of the polyeondensation reactions may be performed in a single liquid phase. Examples of this are the reaction of diisocyanates with diols (8) or diamines (7) and the formation of polycarbonates from bisphenols and phosgene in a solvent with pyridine as the acid acceptor 15, 22),... 

Phosgenation of 2,3-butane diol presents a high potential value in the pharmaceutical field. The cyclic carbonate thus obtained can be photochemically chlorinated to give a vinylene carbonate (I) as depicted in scheme 169 (Ref. 222). 

Besides the many acid sensitive derivatives, base labile protecting groups for 1,2-diols were also recommended. With phosgene or a chlorofoimate, cyclic carbonates are formed from cis- and trans-diols. They are stable to the conditions that hydrolyze acetals but are readily removed by saponification. (Tyclic boronates may also be used, but their application is limited because they hydrolyze very rapidly... 

When a diisocyanate reacts with a diol, a linear polyurethane is generated, and when it reacts with a polyol, it generates a cross-linked polymer. The isocyanates are commonly prepared by the reaction of phosgene and primary amines as follows ... 

Phosgene reacts, sometimes violently, with a large number of common inorganic (Chapter 9) and organic (Chapter 10) substances. Hazardous reactions with lithium, sodium, potassium, aluminium, lithium amide, hexa-2,4-diyn-l, 6-diol, propan-2-ol, and hexafluoropropene have been mentioned specifically [1787]. Mixtures of potassium and phosgene are reported to explode when subjected to shock [1913a]. In addition, phosgene... 

There is thus considerable scope for further examination of the reactions of phosgene with a wide variety of alcohols, diols, aldehydes, hydroxy-aldehydes, epoxides, esters, acids and anhydrides to produce the desired range of chlorinated organic materials. The analogous reactions of COFj and of COCIF will be described in Chapters 13 and 16, respectively. 

The gas phase reaction of phosgene with ethane-1,2-diol over activated charcoal results in the formation of 1,2-dichloroethane with a yield of about 70% at 210 C higher temperatures caused the decomposition of the diol [1C186]. 

Reaction of ethane-1,2-diol with phosgene in the liquid phase gives the... 

Because of the ease with which this cyclization reaction occurs, phosgene has been used as a reagent for the enantiomeric resolution of 1,2- and 1,3-diols [1151,1152] ... 

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